This invention relates generally to X-ray diagnostic systems and relates, more particularly, to a scintillator screen used in such a system.
During use of a diagnostic X-ray system, a scintillator screen is disposed in the path of an X-ray beam on the side of a patient opposite the X-ray source. The scintillator screen produces light in response to a pattern of X-rays impinging upon the screen, and the produced light can be 1) used to expose a film supported adjacent the screen, 2) produce photoelectrons which can then be accelerated in an electric field to strike a second scintillating screen, as in an X-ray image intensifier, or 3) be focused with a lens onto a CCD or other TV camera system for digital image recording.
It would be desirable in some X-ray applications, such as intravenous coronary angiography using K-emission X-rays produced by high energy electron bombardment of high-Z anode materials, to provide a scintillator screen with a reduced sensitivity to X-rays within a preselected energy range. For example, in intravenous coronary angiography during which X-rays are directed through a patient and onto a scintillator screen, it would be desirable to control or limit the amount of light generated in the screen by the higher energy X-rays.
Accordingly, it is an object of the present invention to provide a new and improved scintillator screen for an X-ray diagnostic system having a predetermined sensitivity to X-rays within a preselected energy range.
Another object of the present invention is to provide such a screen which is well-suited for use in a dual-energy screen assembly with which X-rays within one energy range can be distinguished from X-rays within another energy range.
This invention resides in a scintillator screen for an X-ray system comprised of a substrate of low-Z material and bodies associated with the substrate including a high-Z material. At least one of the materials of the bodies and substrate is adapted to scintillate upon exposure to photoelectrons produced by X-rays passing through the high-Z material of the bodies, and the bodies are of such size and are spacially separated from one another by the low-Z material of the substrate to provide the screen with a predetermined sensitivity to X-rays within a preselected energy range.